1. Grass carp generally like to live in the middle and lower layers of rivers, lakes and other waters and coastal areas with more aquatic plants. Mature individuals, with the migration habit of rivers and lakes, lays eggs in rivers and flowing water. After spawning, parent fish and juvenile fish enter tributaries and Tongjiang lakes, and usually feed and fatten in submerged shoals and submerged areas, as well as in water bodies attached to main tributaries (lakes, rivers, harbors and other water-covered areas). Overwintering in the deep water of the main stream or lake in winter. Grass carp is a typical herbivorous fish, with lively temperament, fast swimming speed, often foraging in groups and gluttony. The larvae feed on zooplankton, while the larvae feed on insects, earthworms, algae and duckweeds. When the body length is about 10 cm, they feed entirely on aquatic higher plants, especially Gramineae plants.

2. As producers, green plants and all autotrophs are at the starting point of the food chain, and together they constitute the first trophic level. All animals that feed on producers (mainly green plants) are in the second trophic level, that is, herbivore trophic level. The third trophic level includes all carnivores that feed on herbivores. By analogy, there will be a fourth nutrition level and a fifth nutrition level.

So grass carp belongs to the second trophic level, which is upstairs.